Grinding wheel mounting



March s, 1938. y H, w, Hf BETH 2,110,619

GRINDING WHEEL MOUNTING Filed Jan. 4, 1936 l1 Q ya K sgg! i 4, Ig!

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me/nm HUGE l/V. H. BETH Patented Mer. 8, 1938 sars Limit GMNDNG WHEEL MOUNTING Application January 4, 1936, Serial No. 57,622

1 Claim.

The invention relates to abrasive wheels and mountings therefor.

One object of the invention is to provide an abrasive wheel and mounting adapted to with@ stand a high degree of heat during grinding. Another object of the invention is to provide 'a multi-part mounting for an abrasive wheel. whereby a tough, heat resistant cement may be used. Another object of the invention is to provide a stronger union between abrasive wheel and mounting under varied conditions of practical use. Another object of the invention is to provide a combined abrasive Wheel and mounting construction for connection to speciiic spindle Y flanges. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the fea'- tures of construction, combinations of elements. and arrangements. or parts, as' will be exempliiied 2O in the structure to be hereinafter described, and

the scope of the application of which will be indicated in the following claim.

In the accompanying drawing, in which is shown one of various possible embodiments of 2 5 the mechanical features of this invention,

Fig. l is a plan view of one-half of an annular grinding Wheel and mounting plate constructed in accordance with the invention;

Fig. 2 is an axial sectional view of the wheel 30, and mounting of Fig. l; and

Fig. 3 is an axial sectional view similar to Fig. 2 illustrating a modification of the invention, the grinding wheel being substantially a disk as distinguished from an annulus, and an additional 35 mounting plate being provided in order' to permit attachment to a pre-existing iiange on a wheel spindle.

As conducive to a clearer understanding of the present invention, it is noted that there are particular grinding purposes for which a wheel grinding on a radial surface is preferred. It is often a requirementin such a grinding operation that there shall be nothing projecting beyond the plane of the grinding face in the direction away from the supporting spindle or other supporting means. To mount such grinding wheels. there have been proposed hitherto both soft and hard rubber as a cement uniting the wheel to a backing plate which can be readily attached to a spindle. By soft rubber is meant a rubber vulcanized with a relatively small amount of sulphur, which rubber is reasonably resilient. By hard rubber is meant that substance sometimes called ebonitevv which is vulcanized with a larger amount of sul- 55 phur, usually 20% or more, and. which is relatively rigid. Hard rubber has an advantage over soft rubber, in that it has greater tensile strength, and no cement however great its properties of adhesion can be stronger than the coherence of its particles to each other. Hard rubber has the further advantage that it is less susceptible to thermal shocks, and sometimes` wheels such as herein mentioned are called upon to do so much work that overheating occurs, therefore making the resistance to heat of the cement a factor of importance. On the other hand, as a steel or iron backing plate is usually used on account of its strength and other desirable qualities, and as the coeiiicient of expansion of steel or iron is different from that of many grinding wheels, soft rubber has the advantage that, being resilient, differences ci coefcient of expansion become immaterial, While hard rubber, having no such resilient or plastic qualities, or to a lesser degree, there has been experienced rupturing of the cement in cases Where the diameter ofthe wheel was large. f

Referring now tonFigs. 1 and 2, I provide a grinding wheel I@ shown as a cylindrical annulus, the radial face Il vbeing the grinding face. This grinding wheel Il] is to be secured to a spindle I2 having an integral disk-like iiange I3 with a plurality of tapped holes M. The spindle I2 may be mounted in any suitable bearings and rotated in any suitable manner and may be part of a complete machine, not shown. There is no particular signicance tothe orientation of the axis ofthe spindle I2 inthe present drawing, and actually the spindle l2 might be inverted from the position shown, or might be horizontal, or might be positioned in any `other position desired. I provide a plurality of sectors of an annulus I5, preferably made of steel since steel provides the desired strength and is relatively inexpensive. These sectors when placed adjacent each other form a broken annulus separated by narrow spaces I6. I provide a disk il, also preferably of steel, having an annular outer portion I S which is thinner than the inner portion thereof I9, which portions are separated by a cylindrical shoulder 20. The sectors I5 are secured to the portion I8 and completely cover said portion except for the narrow spaces or grooves I 6. The sectors I5 may be fastened to the portion It of the disk I'I by means of screws 2l, there being counterbored holes 22 in the sectors IES. Thus the disk I'l and sectors I5 together form subn stantially a` disk, which however is broken by the grooves IB and by a narrow annular slot 25 between the shoulder 20 and the sectors I5. Al-

though sectors i5 are attached to the disk I'I by the screws 2l, there is a certain resiliency to the screws and within the limits of expansion and contraction due to heat the sectors I 5 may be said to be independent of each other.

I now secure the grinding wheel I El to the sectors I5 by a hard rubber cement in the following manner. Sandblasting the outside of the sectors I5, I place a thin annular sheet (for example v thick) of unvulcanized hard rubber composition, being milled rubber containing 20% or more of sulphur, upon the sectors I5, and then place the grinding wheel I in matchingr relation upon the rubber, and with its outer circle coinciding with the outer circle of the sectors I5, and secure the parts together with ordinary screw clamps. I now place the clamped plate and wheel with the unvulcanized hard rubber composition between them in the vulcanizing oven and vulcanize at a temperature and for a length of time which is well understood by those cognizant with the manufacture of hard rubber, for example ill hours at l60 C. I use a sufficient number of clamps to secure intimate union of the surfaces of the grinding wheel I9 with the rub-ber. Because free access is provided to the screws 2i, both before and after vulcanizing,i I may cement the sectors I to the wheel Iii prior to the attachment of the sectors to the disk Il, but the procedure rst described is preferred as it is simpler.

The wheel and plate are now securely fastened together and in the cooling of the combined article from vulcanizing temperature, cracks do not appear on account of the fact that the cemented and vulcanized areas have no dimension which is so great as to create enough differential of eX- pansion to break the rubber, at least when the article is embodied in a wheel and plate having a diameterl not greater than 30" with eight sectors according to the present drawing, and a considerably larger article may be successfully made using a greater number of sectors. As pr'eviously stated, radial expansion is taken-care of by relative motion at the screws 2|, and the holes 22 may be slightly oversize and the screws 2| not fully tightened until after the vulcanizing operation'. Even after the screws 2| are tightened, and when the wheel heats up in use, there is sufcient give and resiliency to the screws to permit the relative movement without fracture.

If the spindle I2 has a locating center projection 3l, the disk I'I will be provided with a matching central hole 32. The disk Il has counterbored holes 33 matching the holes I4 for attachment of the assembly to the flange I3 of the spindle I2. It will be understood that spindle flanges I3 are already existing and therefore, from the standpoint of the grinding Wheel manufacturer, unchangeable things which are to be tted with a mating mounting for a grinding wheel; otherwise, and in the case of suiciently large flanges I3 which are or can be provided with the required number of holes, the sectors I5 may be attached directly to the spindle flange I3, provided that a suitable template is provided in order to locate the counterbored holes 22 in desired position.

Referring now to Fig. 3, I have therein shown a grinding wheel Illa. which is substantially a disk, having a relatively small central hole 35, and it may be understood that in some cases there will be no central hole. For the mounting of this wheel Illa which is to grind on a iiat face IIa, I provide sectors I5 as described, and I may provide a disk I'I as already described for the attachment of the sectors I5 thereto. In fact the construction of all parts excepting the grinding wheel is the same as already described in the case of the embodiment of Figs. 1 and 2, excepting that the holes I4a are not tapped, nuts Mb being provided instead, in order that the wheel and mounting maybe readily removed from the spindle I2. Also, in case it is desired to be able to use the disk I'I again after the wheel has been used up, without difficulty owing to inaccessibility of the screws 2|, instead of providing threaded holes in the portion I8 for the screws 2i, I may provide nuts 2Ia. The wheel Illa. and sectors I5 in the embodiment of Fig. 3 may be secured together by vulcanized hard rubber cement 30a according to any of the methods already described.

While vitried wheels may be particularly noted, the invention is likewise applicable to other types of grinding wheels, such as silicate bonded grinding wheels, cement bonded grinding wheels, rubber, shellac, and artificial resin bonded grinding wheels, and any abrasive material whatsoever may be used to form the grinding wheel.

It will thus be seen that there has been provided by this invention an article in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or illustrated in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

I claim:-

An abrasive wheel mounting comtpris'ing a bonded abrasive wheel, a circular mounting plate for attachment to a machine spindle, means on the mounting plate for attaching the plate to said spindle in axial alignment of the plate and spindle, a plurality of sectors cemented to the back of the abrasive wheel, and means attaching the sectors to the mounting plate.

HUGO W. H. BETH. 

